Process of electrically reducing oxid ores.



@10.858,621. PATBNTBD JULY z, 1907. A. J. PBTBRssoN. PROCESS 0F ELECTRIGALLY RBDUGING OXID oREs.

APPLICATION FILED '00T.30, 1906.

2 SHEETS-SHEET l.

Inventor. .r/WG

Witnesses.

A. J. PETERSSON.

PROCESS OP ELEGTRIGALLY REDUGING OXID DRES.

Arrmoulon FILED ooT.ao,19oe.

PATENTBD JULY 2. 1907.

2 SHEETS-SHEET 2.

Witnesses. Inventor.

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@Pim

ALBERT JOHAN PETERSSON, OF ALBY, SWEDEN.

PROCESS OF ELECTRICALLY REDUCING OXID GRES.

Specification of Letters Patent.

Patented July 2, 1907.

Application tiled October 30. 1906. Serial No. 341,342.

To all whom. iL may concern:

Bc it known that I. ALBERT JOHAN PETERSSON, a subject of the King ot' Sweden, and a resident of Alby. Sweden, have invented certain vnew and useful ln1 proveinents in `Processes ot' lllectrically Reducing Oxid (lrcs and the Like; and l do hereby declare the following to he a full, clear, and exact description of the inverttion, such as will enahle others skilled in the art. to which it appertains to make and use the same, reference heilig had to the accompanying drawings, and to letters or figures of reference marked thereon, which forni apart of this specification This invention relates to a proccsss of electrically reducing oxid ores, or the like ores, and other oXids or combinations of oxids while using as reducing agent carhon or carhonic oxid obtained from the carbon of the charge.

The oliject ot' the invention is to render it possible to carry out the reduction processes continually and at a very high heating effect of the electric current.

ln my Swedish Letters Patent No. H862 ot i900 lV have described a. process of producing in the electric 'ay reducing gases, especially carbon-ic oxid, and the use et' such gases for carrying out metallurgical reduction processes in separate furnaces. The carrying out of the said process is. however, connected with special dilliculties as soon as a high temperature is required foi` the reduction. in as ni uch as it is im possible h v means of the gas produced in accordance with the said process to ohtain an intense. heat dependingr on the small heat capacity ol the cas and on the losses of heat caused hy the metallurgical process and the production of gas heinscr carried out in separate furnaces. I

Further, it has heen priiposed to carry out metallur gie-al processes in such a manner that the material to he treated and earhon aie introduced in one and the same furnace in separate lay'. s.,thc material to he reduced heiircr directly suhjected to the action of an electric arc or fortuin.; a resistance iu an electric circuit, while carhonic oxid or other reducing gases are hrought to circtl late through the furnace. ln such method the material 'to he reduced thus will he heated toa higher temperature than the adjacent.layersof carlton. and the method, therefore. in the mostcases cannotv he used [or the reduction el' such ores and the like, as are reduced at a lower temperature than carhonic acid in as much as the temperature ou account of heat heiligr hound in the reduction of the ore, or the like. tends to keep itself at the amount which corresponds to the temperature ol' reduction of the material so that the adjacent layers; of carhon will ohiain a lower temperature than would he required for the reduction of the carhouic acid which is formed in the reduction of the ore. or the like. Moreover. the electrodes will in an essential de ree partake in the re duction so that they will rapidly he consumed and l thereby make the product more expensive than otherwisc.

The present invention relates to a process of reducing and meltingf whereby it will he possible to utilize in an economical manner the heat developed by the electric current and at the same time to obtain a small consumption of the electrodes andan effective regeneration of the gases of carhonieOXid used for the performance ofthe process independently of the reduction temperature ofthe material which is treated.

The invention consists, principally, in charging the ore. or the like., and the carbon into one and the same electric furnace hut in separate layers which are indirect contact with each other. and leading the electric Current through the layer or layers of carhon. ln this` method the carhon will he more intensely lie-ated than the other part of the charge and may without ditliculty he heated to such a high temperature asis required for an effective reduction of carhonic acid into carhonitoxid, while simultaneously the electr-(ales` through which the elect ric current is introduced into the cha rge, may he effectively prevented from heing consumed. Moreover, the transfer of .heat from the carhon to the other part of the charge on account ol' direct conduction and hy means of circulating,r gases will he ohtained sul14 ticiently `great. for the performance of the process, losses of heat and greater falls of temperature heing climi` nated on account. ol the parts of the charge heing in close proximity to each other. The reduced metal will at,` least partially melt hy the influence or' the intense heat ei the transition layers netween the earhon and the ore when the latter' are in direct contact with each other, and is accumulated in a `suitahle reservoir in the hottom of the furnace, and the said melting.,Y action may eventually he sustained hy inducting in the melted mass secondary currents hy means ot suit'ahle transformer devices.

The inventori will he more particularly deserihed herehelow with reference to the acctnipanyingr drawings illustrating diagrammatically a furnace-plant for carrying out the process.

Figure l shows a vertical longitudinal section of th` furnace. Fig. 2 shows; a horixontal section on line llt-ll in Fig. l, and Fig. 3 shows a central vertical section of the furnace.

VReferring to the drawing, the furnace shown has three shafts l. 2 and 3 heing at the top provided with suitahle throats st. and t3 respectively. The shafts l and Ci are adapted to he charged with ore or the like, while the shaft 2 is charged with coal, anthracite or the like heielwlow referred to as carhon. The lower parts of the shafts are in open coinmunication with each other hut nevertheless the carhon and the ore` or the like, also here forni substantially separate layers or columns, the columns of ore closely surrounding the coluinnof carbon.- The lastmentioned part of the furnace constitutes the reductionand melting-zone proper.

For introducing the electric current into the furnace electrodes 7 and 8 are inserted in the lower parts of the walls of the furnace at such places that the column of v carbon will come into contact with the same, while the said electrodes not at all or only in little degree will come in contact with non-reduced ore or with the gases which in the manner described herebelow arc brought to circulate through the furnace, the electrodes on account thereof being effectively prevented from being consumed. At the-bottom of the furnace two reservoiis 9 and 10 are provided, which at the one end may be in communication with a receiver l1 provided at different heights with outlets l2 and 13 for the slag and the melted metal respectively. At the other end the said reservoirs 9 and l0 may be connected to each other and incluse a transformer core l5 having a suitable secondary coil 14, whereby strong secondary currents may be induced in the melting bath in order to facilitate the melting of the reduced metal.

In the side-walls of the reductionand meltingzone of the furnace are provided a number of channels 16 and 17 communicating with regenerators 18 and 19 respectively on each side of the furnace. The outer ends of the said regenerators are by means of a pipe 20 and a ventilator or the like 21 connected to each other, so that the same together with the lower part of the furnace chamber constitute a closed circulation system. At the top the shafts 1 and 3 are provided with outlets 22 and 23 respectively for the excess of gases generated in the system.

The furnace plant described above works as follows: When the furnace has been charged about to the height indicated in Fig. 1, the lower part of the carbon column is heated to incandescence by leading an electric current through the electrodes 7 and 8 and the intermediate part of the column of carbon. Hereby also the adjacent portions of the charge of ore will obviously be heated to a high temperature. When the required temperature has been obtained in the lower part of the furnace, the Ventilator 21 is put in operation, for instance in such a direction that the gases in the system are brought to circulate in the direction of the arrows 24. The said gases consist in the starting substantially of air which when circulated effects a burning of a part of the carbon into carbonic oxid, and at the same time the said air is intensely heated when passing through the column of carbon. The carbonic oxideffects the redliction of a part of the ore below the shaft l during formation of carbonio acid which dilutes the circulating gasmixture. 'lhe latter will thereupon enter the regenerl ator l through the channels 16 and delivers there the main part of its heat, so that the gas-mixture will pass the ,pipe 2() and the ventilator 21 in a comparatively cold condition, whereby losses of heat and injuries on the ventilator otherwise caused by a too strong heating of the same will be obviated. The gases thereupon fiow through the regenerator 19, the channels 17 and the column of ore below the shaft 3, whereupon they will again pass through the glowing column of carbon below the shaf t 2 where they will be reheated and the carbonio acid contained in thegas-mixture will be converted into carbonic oxid by taking up carbon from the column of carbon. When the gases come into the column of ore y below the shaft 1 they are thus again capable of reducing another quantity of ore While consuming a part of the carbonic oxid which by the oxygen of the ore is converted into carbonio acid. In such manner the circulation will go on continually, and the result will be that the gas inclosed in the system is successively converted into carbonic oxid formed by the carbon of the charge and the oxygen of the ore, the excess of gas flowing off through the shafts 1 and 3 and the outlets 22 and 23. When the main-part of the circulating gas has been converted into carbonio oxid, the reaction takes place fully effectively during a continuous oxidizing of the car-- bonic oxid in the column of ore and a subsequent reduction of the carbonic acid formed in the column of carbon. Simultaneously heat is transferred by the circulating gas to the column of ore below the shaft 1 and to the regenerator 18 which absorbs the remaining heat of the gas. By the said transfer of heat and by direct conduction of heat from the glowing column of carbon the reduced metal will melt and drop down into the reservoir 9. 8o

When the desired quantity of heat has been stored up in the regenerator 18, the ventilator 21 is reversed so that the gas will circulate from the ventilator through the pipe 20, the regenerator 18, the channels 16, the column of ore below the shaft 1, the column of carbon below the shaftl 2, the column of ore below the shaft 3, the channels 17, and the regenerator 19 back to the ventilator 2l, and so on. The carbonic oxid mixed with cal'- bonic acid absorbs heat in the regenerator 18 when passing therethrough and being heated to a comparatively high degree passes through the partially reduced column of ore below the shaft l and thus does not in any essential degree cool the same. When passing through the glowing column of carbon the carbonic` acid of the mass of gas is reduced andthe whole quantity of gas intense] y heated, so that the same while passing Athrough the column of ore below the shaft 3 is capable ofY effectivelyreducing thesaid ore. Theheat contained in the gas after the passage through the lastmentioned column of orc will be stored up in the regenerator 19, so that the gases circulating through the ventilator and the other outer parts of the circulation system are comparatively cold.

When the regenerator 19 has been sufficiently heated and the regenerator 18 sufficiently cooled, the direction 1 10 of circulation of the gases is again reversed, and the same may thereupon be reversed as often as is required with respect to the heating or cooling of the regenerators or as often as is suitable for the performance of the process. Eventually the reversal of the direction of flow of the gases may be made at so short intervals that the mass of gas pai-taking in the reaction will chiefly, oscillate between the column of carbon and the columns of` ore on each side thereof. The central column of carbon is continually heated by the electric current passing 120] therethrough, the said current thus delivering the heat required for the re-reduction of the carbonic acid, formed in the reduction of the ore, into carbonio oxid, and the heat required for heating the ore and the partial or full melting ofthe reduced metal. The object of the regenerators is to prevent losses of heat otherwise caused] by the heat being movedby means of the circulating gases, the gas in the above described arrangement of the furnace being at a comparatively high temperature when leaving the channels 16 and 17 respectively.

fl (l In order to accelerate the melting of the reduced metal the transformer 14, 15 may be put in operation, whereby in the secondary conductor formed by the melting mass will be induced a strong current heating the melting bath which thereby will be capable of delivering heat to the adjacent reduced parts of the charge. Eventually the' circulation of gas may be lcd through the shafts 1 and 3 whereby the ore in the latter will be preliminary heated and serve as heat storage so that the size of the regenerators may be essentially reduced, or at sufficiently high shafts be dispensed with.

In order to accelerate-the starting of the process the one or both of the regenerators may be previously heated, and eventually the whole furnace system may be tilled with carbonic oxid, before the working is commenced.

In the drawing I have shown double columns of ore and one regenerator at. each side of the furnace. In some cases it may, however, be suflicipnt to use only one column of ore, in which case the direction of circulation of the gas obviously should be kept constant. In order to carry back to the furnace the heat which is moved on account of the circulation of the gases one may in such case use two regenerators which may alternately be connected to the furnace before or after the same counted in 'the direction of circulation, while the ventilator or any other circulation device is arranged between the outer ends of the regenerators relative to the furnace. In large furnace plants any number of columns of charge may be used, oi which every other is a column of ore and every other a column of carbon.

When volatile ores, such ashzinc, are to be reduced, a column of carbon may suitably be arranged on each side oi a column of ore. 'The mixture of metal vapor and carbonic acid formed in the reduction of the ore will hereby always, independently of the direction of circulation, pass through a column of carbon heated to incandescence by the electric current, wherby the carbonic acid will be fully reduced into carbouic oxid` so that the gas-mixture leaving the reduction chamber will, chiefly, contain only metal yaponand carbonic oxid. The metal vapor, therefore, may easily be condensed outside the furnace and accumulated in a suit able reservoir without running the risk of being reoxidized, while the carbonic oxid may be separated and brought to again partake in the circulation.

In some cases the walls between the columns oi' the charge may, in order to prevent the. clectrhl current from taking its way in any essential degree through thc cclumns of ore be extended to the bottom of the furnace and be provided with channels for letting through the gases, whereby the direct contact between the columns of the charge will be prevented. In such case the column or columns of carbon serve chiefly to heat the circulating gases to a high temperature and to con vert the carbonio acid into carbonic oxid. The ore in the said case will be heated chiefly by the circulating gas but generally a special supply oi' heat to the reduced orc will be necessary in order to melt the same. The said supply of heat may be obtained either by using the column of ore as resistance between electrodes of a primary electric circuit, or by rising the melted mass as secondary member oi' a transformer.

i l 1 i i i The above described invention may advantageously be used also for the production of siliceous iron by melting by means of carbon old broken iron or ore and silicic acid or highly siliceous ores respectively. In such case the carbon is charged so as to form a column or layer between the electrodes and to prot-ect the same from being consumed, the said column of carbon being heated by means of the electric current to such a high temperature that it will reduce and melt the other part of the charge. Furnaces may be used of the kind employed for the production of carbid and which have a furnace chamber in the shape of a Crucible and an electrode at the bottom and an upper, central electrode, so that the circulation of gases as well as the heating ofthe melting bath by means of induced currents may be dispensed With.

Having now described my invention, what I' claim as new and desire to secure by Letters latcnt is:

1. 'lhe process oi' reducing oxltl ores and the like by means of carbon, which consists in successively charging the ore and the carbon into an electric furnace so that ore and carbon continuously forni separate upright columns in close contact with each other, and heating the column of carbon by means of electric currents to a reactive temperature to reduce the ore, substantially as and for the purpose set forth.

2. The process of reducing oxd ores and the like by means ot carbon, which consists in successively charging the ore and the carbon into an electric furnace so that orc and carbon continuously form separate upright columns in close contact with each other, heating the column of carbon by means of electric currents to a reactive temperature, facilitating the reduction of the ore by circulating hot reducing gases from the column of carbon to the column of ore. and regenerating said reducing gabscs hy returning them to the column oi' carbon, substantially as and ior the purpose set forth.

3. The process of reducing oxid ores and the like by means of carbon, which consists in successively 'charging the ore and the carbon into an electric furnace so that ore and curhon continuously form separate. upright columns in close contact with each other, heating.: the column of carbon by means of electric currents to u reactive temperature, and facilitating the inciting of thc reduced metal by inducing electric currents in the melted metal. substantially as and for the purpose set'. forth.

4. '.lhe process of reducing oxid ores and .the like by means of carbon. which consists in successively charging the ore and the carbon into an electric furnace so that ore and carbon continuously form separate upright columns in close contact with euch other. heatingY the column of carbon by means of electric currents to a reactive teinperatuic accelerating the reduction ol the orc hy circulating hot reducing gases from the column of carbon through the column of orc. storing.r tho heat, carried away 11i-om the charac by the circulating cuscs. pre-heatingr said ruses hy menus ot' heat previously stored up, und retteneratinc' .said rctlucing gases hy returningr them to the column of carbon. substantially us and for thc purpose set forth.

5, 'l`hc process of reducing' orcs :1nd the, likt` which coniprises introducing the ore and the carbon in separate contacting' columns into :in electric furnace, passingr un electric current through the column of carbon and burning the combustible gases at or about the zone of reduction of the ore.

in testimony that l claim the foregoing as my invention, l have sinned my name in presence ol' two subscribing witnesses.

rillll'lll'l JOHAN llCTHRSSON.

Witnesses l Cini. Fnrnnno, Enzimi Dnnzuan.

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